LED filaments are increasingly used in the production of retrofit lamps for general lighting. In an LED filament, LED chips are arranged on a common linear substrate and encased in a converter layer. When switched on, such an arrangement appears as a classic glowing filament to the viewer. However, a large deviation from the classic filament can be found in the radiation profile, especially with regard to color location and/or brightness distribution. Known LED filaments have a radiation profile that shows large inhomogeneities in brightness and color location, both over a radial angle and over a polar angle. Those inhomogeneities also lead to inhomogeneous illumination in the end product, for example, in an LED retrofit lamp.
It could therefore be helpful to provide a filament and a light source including a plurality of filaments having an improved radiation profile, which has a particularly low inhomogeneity in brightness and/or color location.